The Japanese manufacturer partnered with Toro Rosso heading into 2018 after its divorce from McLaren following a disastrous three-year tenure which was hampered by recurring reliability woes and a lack of power.

Honda’s impressive progress with Toro Rosso has convinced Red Bull to cut its Renault ties in favour of a switch to the same power unit used by its sister squad from next season.

“They have so far done a fantastic job because they have improved the performance a lot, and also the reliability,” Tost explained.

“They have exceeded expectations with regards to reliability, because we thought we would have much more problems but to be honest we haven’t had any major issues.

“And also regarding the performance, because with the new specification we are not far away from the top teams.”

Toro Rosso has been encouraged by Honda’s latest engine specification despite facing some setbacks, including a flurry of grid drops for Pierre Gasly and teammate Brendon Hartley after exceeding the permitted allocation of power unit components that can be used throughout the year.

“I’m convinced that Honda will improve during the winter months,” Tost added. “They are doing a very good job, they are pushing very hard.

“How many power units then at the end will be used next year? I don’t know yet. For me, three power units is wrong from the regulation side.

“We should have the possibility to get more but that’s currently within the regulations and I hope that this will change from 2021 onwards.”